Electric valve and refrigeration cycle system

Abstract

To provide an electric valve and a freezing cycle system in which an operability can be preferably maintained by preventing a lock of a drive shaft.SOLUTION: An electric valve 10 includes: a valve body 1; a valve member 2; a drive part (stepping motor 3); a support member 5 configuring a screw feeding mechanism 17 along with a rotor shaft 32; and a valve holder 6 across the valve member 2 and the rotor shaft 32. The valve holder 6 includes: a washer (locked part) 65 locked on a flange part 32c along with a lifting of the rotor shaft 32; and a spacer part (movement restriction means) 67 for restricting a movement of a spring receiver (spring receiver member) 63 toward a base end part side. A relation between a backlash amount B in an axial direction of a screw part in the screw feeding mechanism 17 and a clearance C in an axial direction of the flange part 32c and the washer 65 is set as B<C.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a motor-operated valve and a refrigeration cycle system. [Background technology]

[0002] Conventionally, there is known an electrically operated valve that includes a valve body having a valve port, a valve element that changes the opening degree of the valve port, and a drive unit that drives the valve element forward and backward (see, for example, Patent Document 1). In this electrically operated valve, a screw feed mechanism is formed by the rotor shaft (male thread) of the drive unit and the female thread of the support member, and the valve element has a valve member (needle valve) that moves toward or away from the valve port and a valve holder that connects the rotor shaft of the drive unit and the valve member, and the valve holder is engaged with a flange portion of the rotor shaft to lift up the valve element and open the valve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4541366 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional motor-operated valves such as that described in Patent Document 1, the valve element is driven back and forth by a screw feed mechanism between the male screw on the rotor shaft of the drive unit and the female screw on the support member, with the male screw and the female screw abutting against each other. If the rotor shaft of the drive unit is tilted relative to the female screw, the flange of the rotor shaft also tilts. However, depending on how the tilted flange abuts against the inside of the valve holder, the flange may also abut at two or more points in addition to the male screw abutting against the female screw. If the rotor shaft, including the flange, is driven back and forth while abutting at three or more points in this way, the rotor shaft may lock depending on the state of the abutment, resulting in a problem of reduced operability.

[0005] An object of the present invention is to provide an electric valve and a refrigeration cycle system that can prevent the locking of a drive shaft and maintain good operability.

Means for Solving the Problems

[0006] The electric valve of the present invention includes a valve body having a valve chamber and a valve port, a valve member for changing the opening degree of the valve port, a drive unit having a drive shaft for driving the valve member to advance and retreat in the axial direction of the valve port, a support member constituting a screw feed mechanism together with the drive shaft, a valve holder extending between the valve member and the drive shaft, and a holder guide for guiding the valve holder in the axial direction. The electric valve converts the rotational motion of the drive unit into a linear motion in the axial direction of the drive shaft by the screw feed mechanism, and controls the opening degree of the valve port by the valve member connected to the drive shaft. The drive shaft has a flange portion formed in a flange shape at the tip on the valve member side. The valve holder has a generally cylindrical holder body, a spring receiving member provided between the tip of the drive shaft and the base end portion of the valve member, and a compression spring provided between the spring receiving member and the base end portion of the valve member for pressing and biasing the valve member. The valve holder is provided with an insertion hole formed at the base end portion of the holder body for inserting the tip of the drive shaft, a locked portion that is locked to the flange portion as the drive shaft rises, and a movement restricting portion for restricting the movement of the spring receiving member biased by the compression spring toward the base end portion side. The relationship between the axial backlash amount B of the screw portion constituted by the drive shaft and the support member in the screw feed mechanism, and the axial clearance C between the flange portion and the locked portion in a state where the movement of the spring receiving member is restricted by the movement restricting portion and the tip of the drive shaft is in contact with the spring receiving member, is set such that B < C.

[0007] According to such an invention of the present invention, since the axial clearance C between the flange portion of the drive shaft and the engaged portion is set larger than the axial backlash amount B of the screw portion in the screw feed mechanism (B < C), even if the drive shaft is inclined with respect to the support member, it becomes difficult for the flange portion of the drive shaft to contact at two or more locations within the valve holder, preventing the drive shaft from locking and maintaining good operability of the electric valve. That is, the state where the movement of the spring receiving member is restricted by the movement restricting portion and the state where the tip of the drive shaft contacts the spring receiving member means that the biasing force of the compression spring on the drive shaft does not act and the flange portion of the drive shaft does not lock the engaged portion. Therefore, since the force restricting the deflection of the tip portion of the drive shaft is zero or small, the drive shaft is likely to tilt. Even in such a state where the drive shaft is likely to tilt, if the axial clearance C between the flange portion of the drive shaft and the engaged portion is set larger than the backlash amount B of the screw portion, in addition to the contact between the male screw portion and the female screw portion, it is possible to suppress the contact of the flange portion at two or more locations within the valve holder, that is, to suppress the contact of the drive shaft including the flange portion at three or more locations, and prevent the drive shaft from locking.

[0008] At this time, it is preferable that both the outer clearance W1 and the inner clearance W2 in the radial direction of the screw portion in the screw feed mechanism are set smaller than the clearance C (W1 or W2 < C). According to this configuration, since the outer clearance W1 and the inner clearance W2 in the radial direction of the screw portion are set smaller than the clearance C, the radial deflection of the drive shaft can be restricted, and the tilt of the drive shaft can be suppressed.

[0009] Furthermore, it is preferable that the radial clearance CL1 between the valve holder and the holder guide, the radial clearance CL2 between the flange portion of the drive shaft and the movement restricting portion, and the radial clearance CL3 between the drive shaft and the engaged portion are all set to be larger than the clearance C (C < CL1 or CL2 or CL3). According to this configuration, since the clearances CL1, CL2, and CL3 of each part related to the drive shaft and the valve holder are set to be larger than the clearance C, even when the drive shaft is inclined, a gap can be secured at the clearances CL1, CL2, and CL3 of each part. Therefore, it is possible to prevent the flange portion of the drive shaft from abutting at two or more locations and prevent the locking of the drive shaft.

[0010] The refrigeration cycle system of the present invention is a refrigeration cycle system including a compressor, a condenser, an expansion valve, and an evaporator, characterized in that any one of the electric valves is used as the expansion valve.

Advantages of the Invention

[0011] According to the electric valve and the refrigeration cycle system of the present invention, it is possible to prevent the locking of the drive shaft and maintain the operability of the electric valve well.

Brief Description of the Drawings

[0012] [Figure 1] It is a longitudinal sectional view showing an electric valve according to an embodiment of the present invention. [Figure 2] It is a longitudinal sectional view showing an enlarged main part of the electric valve. [Figure 3] It is a longitudinal sectional view explaining the operation of the electric valve and a conventional electric valve. [Figure 4] It is a longitudinal sectional view showing an enlarged screw part of the electric valve. [Figure 5] It is a longitudinal sectional view showing an enlarged other main part of the electric valve. [Figure 6] It is a view showing an example of the refrigeration cycle system of the present invention.

Embodiments for Carrying Out the Invention

[0013] A motor-operated valve according to an embodiment of the present invention will be described with reference to Figures 1 to 5. As shown in Figure 1, a motor-operated valve 10 of this embodiment includes a valve body 1, a valve element 2 as a valve member, a stepping motor 3 as a drive unit, and a valve port 14. Note that the concepts of "upper and lower" in the following description correspond to the upper and lower in Figure 1.

[0014] The valve body 1 has a cylindrical valve housing member 1A, a valve guide member 1B as a valve guide portion fixed inside the valve housing member 1A, a cylindrical case 4 fixed to the top of the valve housing 1A, and a support member 5 fixed to the upper end opening of the case 4.

[0015] A substantially cylindrical valve chamber 1C is formed inside the valve housing member 1A, and a first coupling pipe 11 is attached to the side surface of the valve housing member 1A, communicating with the valve chamber 1C. The valve housing member 1A also has a valve port 14, which is a cylindrical valve opening, formed in the center of a valve seat portion 13. A rim 1b is formed at the top end of the valve housing member 1A, surrounding the valve guide member 1B. A cylindrical portion 15, which has a portion of the valve port 14 inside, is formed at the bottom surface of the valve housing member 1A. A second coupling pipe 12, which communicates with the valve chamber 1C, is positioned coaxially with the valve port 14 on the outer periphery of the cylindrical portion 15 and is attached to the bottom of the valve housing member 1A by brazing. When a refrigerant flows in as a fluid from the first coupling pipe 11, the refrigerant flows out of the second coupling pipe 12 via the valve chamber 1C. When refrigerant flows in from the second joint pipe 12, the refrigerant passes through the valve chamber 1C via the valve port 14 and flows out from the first joint pipe 11. The cylindrical portion 15 has a cylindrical inner circumferential surface that is continuous with the valve port 14 of the valve housing member 1A, and is molded integrally with the valve housing member 1A.

[0016] The valve guide member 1B is press-fitted from above the valve housing member 1A and attached while inserted into the valve chamber 1C, and this valve guide member 1B has a valve guide hole 16 formed around the axis L. The case 4 is assembled so as to fit onto the outer periphery of the rim 1b of the valve housing member 1A, and is fixed to the valve housing member 1A by crimping the rim 1b and brazing the outer periphery of its bottom.

[0017] The support member 5 is welded to the upper opening of the case 4 via a fixing bracket 41. A female threaded portion 5a formed coaxially with the axis L of the valve port 14 or the like is provided in the center of the upper side of this support member 5, and a cylindrical guide hole 5c having an inner diameter larger than the outer periphery of the female threaded portion 5a is formed on the lower side. In the present embodiment, the support member 5 is fitted into the upper opening of the case 4 in a welded and fixed state via the fixing bracket 41, but the support member 5 may also be press-fitted into the case 4.

[0018] The valve disc 2 has a rod shaft 22 as a shaft portion with a needle portion 21 provided at its lower tip, and a valve holder 6 that holds the upper end of the rod shaft 22. The rod shaft 22 is slidably inserted into the valve guide hole 16 of the valve guide member 1B in the direction of the axis L. A flange portion 23 is formed at the upper end of the rod shaft 22. The needle portion 21 provided on the rod shaft 22 is connected to a seating surface portion 21a of the needle portion 21 that seats on the valve seat portion 13 when the valve disc 2 is moved to the lowermost position and in the fully closed state, and is formed so that its diameter decreases toward the tip. The valve disc 2 may be configured so that a small opening can be obtained by not having the needle portion 21 contact the valve seat portion 13 even when the valve disc 2 is moved to the lowermost position and in the fully closed state (i.e., when it is closest to the valve seat portion 13).

[0019] The valve holder 6 has a boss (valve support) 62 fixed to the lower end of a cylindrical portion 61, and includes a spring retainer 63, a compression coil spring 64, a washer 65, and a spacer 67 inside the cylindrical portion 61. The upper end of the rod shaft 22 is inserted into a fitting hole 62a of the boss 62, and the flange 23 of the rod shaft 22 abuts against the boss 62 to hold the upper end of the rod shaft 22. The valve holder 6 is inserted into a guide hole 5c serving as a holder guide in the support member 5 and is supported so as to be slidable in the direction of the axis L. The valve holder 6 is provided at one end on the valve port 14 side with the valve disc 2 suspended therefrom, and houses a compression coil spring (compression spring) 64 that biases the valve disc 2 and the spring retainer 63 in a direction separating them. The other end of the valve holder 6 is connected to a rotor shaft 32 (described later) serving as a drive shaft. At least one of the valve element 2 and the rotor shaft 32 is connected to the inside of the valve holder 6 so as to be able to move forward and backward while being prevented from coming off from the valve holder 6.

[0020] In this embodiment, the thickness of the flange portion 32c of the rotor shaft 32 is thinner than the height of a recess 67a formed in a spacer portion 67 disposed between the washer 65 and the spring retainer 63 in the valve holder 6, in which the flange portion 32c is accommodated. In other words, a gap is provided between the flange portion 32c and the recess 67a of the spacer portion 67. Therefore, in the valve open state, the biasing force of the compression coil spring 64 is not transmitted to the rotor shaft 32, and the valve holder 6 is suspended from the rotor shaft 32. The biasing force of the compression coil spring 64 acts on the rotor shaft 32 via the spring retainer 63 only when the valve is closed. This reduces the influence of backlash between the rotor shaft 32 and the support member 5 on the valve holder 6. Furthermore, because the valve disc 2 is guided by the valve guide member 1B, the valve disc 2 is easily seated on the valve seat 13 without tilting. That is, after the valve disc 2 is seated on the valve seat 13, the rotor shaft 32 moves by the gap between the flange portion 32c and the recessed portion 67a of the spacer portion 67, and the biasing force of the compression coil spring 64 begins to act. This reduces valve leakage. The spacer portion 67 and the spring retainer 63 may be formed integrally.

[0021] Furthermore, the valve holder 6 is inserted into the guide hole 5c of the support member 5 and guided in the direction of the axis L. In other words, the lower side of the guide hole 5c of the support member 5 functions as a holder guide portion 5d that guides the valve holder 6. The holder guide portion 5d may be provided integrally with the support member 5 or may be provided separately from the support member 5.

[0022] The stepping motor 3 as a drive unit has a can 7, a magnet rotor 31 provided in the can 7, a rotor shaft 32 as a drive shaft, a stator coil (not shown), and a rotation stopper mechanism 8 for the stepping motor 3.

[0023] The can 7 is hermetically fixed to the upper end of the case 4 by welding or the like and houses the support member 5 and magnet rotor 31. The magnet rotor 31 has a multi-pole magnetized outer periphery, and a rotor shaft 32 is fixed to its center. When the valve is closed, the lower end of the rotor shaft 32 penetrates the upper end of the cylindrical portion 61 of the valve holder 6 and abuts against the upper surface of a spring bearing 63. A retaining flange 32c is held within the cylindrical portion 61 via a washer 65. The rotor shaft 32 also has a male thread 32a formed on the upper surface of its middle portion. This male thread 32a is threadedly engaged with a female thread 5a of the support member 5. These male thread 32a and female thread 5a form the screw feed mechanism 17 of the drive unit. The screw feed mechanism 17 converts the rotational motion of the stepping motor 3 into linear motion of the rotor shaft 32, thereby driving the valve element 2 back and forth along the axis L. The stator coil is disposed on the outer periphery of the can 7, and when a pulse signal is given to this stator coil, the magnet rotor 31 rotates in accordance with the number of pulses, causing the rotor shaft 32 to rotate.

[0024] The rotation stopper mechanism 8 of the stepping motor 3 has a guide support 8A fixed to the ceiling of the can 7, and the guide support 8A is equipped with a cylindrical guide 86 that hangs down along the axis from the center of the ceiling of the can 7, a screw guide 87 fixed to the outer periphery of the guide 86, and a movable slider 88 that is guided by the screw guide 87 and can rotate and move up and down. The movable slider 88 is provided with claws 88a that protrude radially outward, and the magnet rotor 31 is provided with extensions 31a that extend upward and abut against the claws 88a. When the magnet rotor 31 rotates, the extensions 31a press the claws 88a, causing the movable slider 88 to rotate and move up and down along the screw guide 87. A tubular member 8B that guides the upper part of the rotor shaft 32 is fitted inside the cylindrical guide 86.

[0025] The screw guide 87 is formed with an upper end stopper 87a that determines the uppermost position of the magnet rotor 31, and a lower end stopper 87b that determines the lowermost position of the magnet rotor 31. When the movable slider 88, which has descended in conjunction with the forward rotation of the magnet rotor 31, abuts against the lower end stopper 87b, the movable slider 88 becomes unable to rotate at this abutting position, thereby restricting the rotation of the magnet rotor 31 and stopping the descent of the valve disc 2. On the other hand, when the movable slider 88, which has ascended in conjunction with the reverse rotation of the magnet rotor 31, abuts against the upper end stopper 87a, the movable slider 88 becomes unable to rotate at this abutting position, thereby restricting the rotation of the magnet rotor 31 and stopping the ascent of the valve disc 2.

[0026] The structure of the stepping motor 3 as the driving part of the motor-operated valve 10 is the same as that described above. The shape is not limited to one having an extension portion 31a that abuts against the claw portion 88a of the movable slider 88, but may also be one in which, for example, a coil-shaped driven slider having a claw portion is screwed into a guide groove of a support member.

[0027] Next, the relationship between the screw feed mechanism 17 of the drive unit of the present embodiment and the suspension structure of the valve holder 6 by the rotor shaft 32 will be described with reference to FIG. 2. In the screw feed mechanism 17, a screw portion that is screwed together by the male screw portion 32a of the rotor shaft 32 and the female screw portion 5a of the support member 5 is formed. This screw portion has backlash in the axial direction of the axis L, and the amount of this backlash is denoted as B. Further, in the valve holder 6, a spring receiver (spring receiver member) 63 urged by a compression coil spring 64 abuts on a washer (locked portion) 65 via a spacer portion (movement restricting means) 67, that is, the movement of the spring receiver 63 is restricted by the spacer portion 67, and the clearance in the axial direction between the upper surface of the flange portion 32c of the rotor shaft 32 and the lower surface of the washer 65 in a state where the tip 32d of the rotor shaft 32 abuts on the spring receiver 63 is denoted as C. The relationship between this backlash amount B and the clearance C is set such that B < C.

[0028] Since the relationship between the backlash amount B and the clearance C is set such that B < C, as shown in FIG. 3(A), when the rotor shaft 32 starts to rise and the screw engagement between the male screw portion 32a and the female screw portion 5a loosens, even when the rotor shaft 32 tilts with respect to the axis L based on the backlash amount B, the upper surface of the flange portion 32c of the rotor shaft 32 abuts on the washer 65 as in the A1 portion of FIG. 3(A), but the tip 32d of the rotor shaft 32 does not abut on the spring receiver 63, so contact at two locations does not occur and the rotor shaft 32 is not locked. On the other hand, if the relationship between the backlash amount B and the clearance C is not set such that B < C, as shown in FIG. 3(B), the upper surface of the flange portion 32c of the rotor shaft 32 abuts on the washer 65 as in the A2 portion of FIG. 3(B), and the tip 32d of the rotor shaft 32 also abuts on the spring receiver 63 as in the A3 portion of FIG. 3(B). When contact occurs at two locations in such a state, the biasing force of the compression coil spring 64 also acts on the rotor shaft 32 via the spring receiver 63, so the possibility that the rotor shaft 32 is locked is particularly high.

[0029] According to the electric valve 10 of this embodiment, the axial clearance C between the flange portion 32c of the rotor shaft 32 and the washer 65 is set larger than the axial backlash amount B of the screw portion (male screw portion 32a and female screw portion 5a) in the screw feed mechanism 17 (B < C). Even if the rotor shaft 32 is inclined with respect to the support member 5, in addition to the contact between the male screw portion 32a and the female screw portion 5a, it becomes difficult for the flange portion 32c of the rotor shaft 32 to contact at two or more locations within the valve holder 6. That is, it is possible to suppress the driving of the rotor shaft 32 including the flange portion 32c while contacting at three or more locations. Thereby, it is possible to prevent the rotor shaft 32 from locking and maintain the operability of the electric valve 10 well.

[0030] Also, as shown in FIG. 4, in the electric valve 10 of this embodiment, it is preferable that the outer clearance W1 and the inner clearance W2 in the radial direction of the screw portion (male screw portion 32a and female screw portion 5a) in the screw feed mechanism 17 are both set smaller than the clearance C (W1 or W2 < C). According to this configuration, since the outer clearance W1 and the inner clearance W2 in the radial direction of the screw portion are set smaller than the clearance C, it is possible to limit the radial runout of the rotor shaft 32 and suppress the inclination of the rotor shaft 32.

[0031] Also, as shown in FIG. 5, in the electric valve 10 of the present embodiment, the radial clearance CL1 between the valve holder 6 and the guide hole (holder guide) 5c, the radial clearance CL2 between the flange portion 32c of the rotor shaft 32 and the spacer portion 67, and the radial clearance CL3 between the rotor shaft 32 and the washer 65 are all preferably set to be larger than the clearance C (C < CL1 or CL2 or CL3). According to this configuration, since the clearances CL1, CL2, and CL3 of the respective parts related to the rotor shaft 32 and the valve holder 6 are set to be larger than the clearance C, even when the rotor shaft 32 is inclined, a gap can be ensured at the clearances CL1, CL2, and CL3 of the respective parts. Therefore, it is possible to prevent the flange portion 32c of the rotor shaft 32 from abutting at two or more locations and prevent the locking of the rotor shaft 32.

[0032] Next, the refrigeration cycle system of the present invention will be described based on FIG. 6. FIG. 6 is a diagram showing an example of the refrigeration cycle system of the present invention. In FIG. 6, reference numeral 100 is an expansion valve using the electric valve 10 of the above-described embodiment, 200 is an outdoor heat exchanger mounted on an outdoor unit, 300 is an indoor heat exchanger mounted on an indoor unit, 400 is a flow path switching valve constituting a four-way valve, and 500 is a compressor. The electric valve 100, the outdoor heat exchanger 200, the indoor heat exchanger 300, the flow path switching valve 400, and the compressor 500 are connected as shown in the figure by conduits, respectively, to constitute a heat pump type refrigeration cycle. Note that an accumulator, a pressure sensor, a temperature sensor, etc. are not shown in the figure.

[0033] The flow path of the refrigeration cycle is switched into two paths, i.e., the flow path during cooling operation and the flow path during heating operation, by the flow path switching valve 400. During cooling operation, as shown by the solid-line arrow in FIG. 6, the refrigerant compressed by the compressor 500 flows into the outdoor heat exchanger 200 from the flow path switching valve 400. The outdoor heat exchanger 200 functions as a condenser, and the liquid refrigerant flowing out of the outdoor heat exchanger 200 flows into the indoor heat exchanger 300 via the expansion valve 100. The indoor heat exchanger 300 functions as an evaporator.

[0034] 6, the refrigerant compressed by the compressor 500 is circulated in the following order: from the flow path switching valve 400 to the indoor heat exchanger 300, the expansion valve 100, the outdoor heat exchanger 200, the flow path switching valve 400, and then to the compressor 500, with the indoor heat exchanger 300 functioning as a condenser and the outdoor heat exchanger 200 functioning as an evaporator. The expansion valve 100 reduces the pressure and expands the liquid refrigerant flowing in from the outdoor heat exchanger 200 during cooling operation, or from the indoor heat exchanger 300 during heating operation, and further controls the flow rate of the refrigerant. In Figure 6, the expansion valve 100 is provided in the refrigeration cycle so that liquid refrigerant from the outdoor heat exchanger 200 flows into the first joint pipe 101 of the expansion valve 100 during cooling operation, and liquid refrigerant from the indoor heat exchanger 300 flows into the second joint pipe 102 of the expansion valve 100 during heating operation. However, this is not limited to this, and the expansion valve 100 may be provided in the refrigeration cycle so that liquid refrigerant from the outdoor heat exchanger 200 flows into the second joint pipe 102 of the expansion valve 100 during cooling operation, and liquid refrigerant from the indoor heat exchanger 300 flows into the first joint pipe 101 of the expansion valve 100 during heating operation.

[0035] According to the refrigeration cycle system of the present invention, as described above, the electric valve 10 used as the expansion valve 100 operates well with the rotor shaft 32 prevented from locking, making it possible to create a refrigeration cycle system that is less prone to malfunctions.

[0036] The specific configuration of the refrigeration cycle system of the present invention is not limited to the above-described embodiment, and design modifications that do not deviate from the gist of the present invention are also included in the present invention. For example, in the above-described embodiment, the motor-operated valve 10 is used as an expansion valve in the refrigeration cycle system, but this is not limited thereto, and the motor-operated valve can also be applied to other systems, such as a throttling device on the indoor unit side of a multi-air conditioner for a building. [Explanation of symbols]

[0037] 1 Valve body 1C Valve chamber 2 Valve body (valve member) 21 Needle section 3 Stepping motor (drive unit) 32 Rotor shaft (drive shaft) 32a male thread 32c flange 5 Support member 5a Female thread 5c Guide hole (holder guide) 6 Valve holder 62 Boss part (valve support part) 63 Spring holder (spring holder member) 65 Washer (retained part) 67 Spacer portion (movement restriction means) 10 Motor-operated valve 13 Valve seat 14 Valve port 17 Screw feed mechanism 100 Expansion valve 200 Outdoor heat exchanger (condenser, evaporator) 300 Indoor heat exchanger (condenser, evaporator) 400 Flow path switching valve 500 compressor B Backlash amount C Clearance CL1, CL2, CL3 clearance W1 Outer clearance W2 inner clearance

Claims

1. a valve body having a valve chamber and a valve port; a valve member that changes the aperture of the valve port; a drive unit having a drive shaft that drives the valve member back and forth in the axial direction of the valve port; a support member that constitutes a screw feed mechanism together with the drive shaft; a valve holder that spans the valve member and the drive shaft; and a holder guide that guides the valve holder in the axial direction, wherein the screw feed mechanism converts rotational movement of the drive unit into linear movement in the axial direction of the drive shaft, and the aperture of the valve port is controlled by the valve member connected to the drive shaft, The drive shaft has a flange portion formed in a flange shape at a tip end portion on the valve member side, the valve holder includes a cylindrical holder body, a spring receiving member provided between the tip of the drive shaft and the base end of the valve member, and a compression spring provided between the spring receiving member and the base end of the valve member to press and bias the valve member, The valve holder is provided with an insertion hole formed in the base end of the holder body and through which the tip end of the drive shaft is inserted, a locked portion that is locked to the flange portion as the drive shaft rises, and a movement restricting portion that restricts movement of the spring receiving member biased by the compression spring toward the base end side, a backlash amount B in the axial direction of a threaded portion formed by the drive shaft and the support member in the screw feed mechanism; a clearance C in the axial direction between the flange portion and the engaged portion when the movement of the spring receiving member is restricted by the movement restricting portion and the tip of the drive shaft is in contact with the spring receiving member; The motor-operated valve is characterized in that the relationship B<C is set.

2. The electric valve according to claim 1, characterized in that the radial outer clearance W1 and inner clearance W2 of the screw portion in the screw feed mechanism are both set to be smaller than the clearance C (W1 or W2 < C).

3. a radial clearance CL1 between the valve holder and the holder guide; a radial clearance CL2 between the flange portion of the drive shaft and the movement restricting portion; a radial clearance CL3 between the drive shaft and the locked portion; 2. The motor-operated valve according to claim 1, wherein each of the clearances CL1, CL2, or CL3 is set to be larger than the clearance C (C<CL1, CL2, or CL3).

4. A refrigeration cycle system including a compressor, a condenser, an expansion valve, and an evaporator, wherein the motor-operated valve according to any one of claims 1 to 3 is used as the expansion valve.

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